This invention relates to the field of soil additives for lawns, trees and planter beds.
A number of factors are important in determining the ability of soil to support plant life. Among the crucial factors are the presence of humus and organic matter, together with the availability of essential elements, the ability to retain water, the creation of a good soil structure for microbial activity, cation exchange capacities, sodium absorption ratios, aminization, ammonification, nitrification, pH buffering and mineralization. To properly support plant life, the organic and carbohydrate content of the soil must be in the proper ratio to sand, silt and clay. Moreover, the growth of plant life cannot take place without soil microbes which make available nitrogen to the plants and which break down organic materials.
Cultivation of plants is especially difficult in the sand and clay based soils found, for example, in many areas of southern and central California, as well as Arizona and Nevada. The pH of such soils may be very high, in the range of 7.8 to 8.9. Moreover, very sandy soils are organically deficient, and substantially without microbial activity. In addition, rainfall in such areas is scarce, and water is therefore at a premium, while the soil qualities do not permit retention of water.
The rapidly expanding population of the Southwestern United States, as well as the resort and tourism based economy of many areas relying on golf courses, has made it important to develop methods of economically cultivating grasses and other landscape plants in soils which make such cultivation very difficult. Among the materials suggested for addition to soils to improve cultivation are expanded mica, peat moss, straw, and corn cobs. U.S. Pat. No. 2,780,031 suggests the use of hydrated tricalcium silicate of small particle size for mixture with soils, while U.S. Pat. No. 3,323,898 discloses expanded perlite as a soil amendment material. The use of synthetic resins, such as polyacrylonitriles, and polyvinyl pyrrolidone is known from U.S. Pat. No. 4,762,545, but these polymeric materials tend to be costly.